In domestic electrical appliances or the like such as washers, dishwashers, dryers, and beverage preparation devices, it is important to ensure a high degree of safety of the users of such a device from the possibility of electrical shock due to exposure of the operator or user to a relatively high voltage such as the A.C. line voltage. To ensure the safety of such domestic appliances, safety standards have evolved which must be complied with in order to market such an appliance. For example, one safety standard requires at least 8 millimeter (mm) of air gap and at least 2 mm of insulation gap between portions of the apparatus exposed to line voltage and those parts to be in contact with the operator or user. In addition to electric motors and other line voltage driven controlled elements of such an appliance, the sensors and control components as well as the display devices must meet such a high safety standard when they are electrically connected to the high voltage components of the appliance. Control switches must also comply with the above mentioned standards as there is a probable risk of contact during user operation of the appliance.
Heretofore, it has been conventional practice to drive the input circuit with low voltage in addition to the appliance sensors, the sensors normally being the most readily "touchable" or accessible electrical components of the appliance. However, it is desirable to supply such a domestic appliance with line voltage power supply such as the conventional 110 V. A.C. line power. If such a high voltage power supply is to be used to power the appliance, the low voltage circuitry must be separated from the line driven circuitry according to prescribed safety standards. Accordingly, it is desirable to electrically isolate the user accessible electrical components of domestic appliance from the AC line voltage so as to isolate the operator or user from a possibility of electric shock.